1. Field of the Invention
The present invention relates generally to the fabrication of probe card for probing electronic devices and, more specifically, to a high conducting thin-film nanoprobe card fabrication method.
2. Description of the Related Art
Future electronic device probing technology will encounter technical challenges in ultra fine pitch, area array testing, high frequency and low cost. Currently, commercialized probing technology for use in high frequency probing includes two types, one is coaxial probe card and ceramic blade probe card, and the other is membrane probe card as disclosed in U.S. Pat. No. 5,090,118. The fabrication of a coaxial probe card or ceramic blade probe card is achieved by mounting coaxial probes or ceramic blade probes in a printed circuit board (PCB) individually. This fabrication cannot satisfy the demand for ultra fine pitch. Further, the maximum probing frequency of a coaxial probe card or ceramic blade probe card reaches 2˜3 GHz only. A membrane probe card is obtained by means of forming metal bumps on a polymeric membrane. The advantage of a membrane probe card is its limited exposed metal area and maximum 20 GHz probing frequency. However, a membrane probe card still has numerous drawbacks as follows:
1. This kind of probe card does not satisfy technical requirement for 40 GHz probing frequency in RF device testing.
2. Due to the limitation of the spring power of polymeric membrane, this kind of probe card cannot compensate test samples for coplanar error; therefore this kind of probe card is not practical for use in multi-DUT (Die Under Test) testing.
3. The manufacturing cost of this kind of probe card is too high (about 2˜3 times over conventional probe cards) to be popularly accepted.